1. Field of the Invention
Modern internal combustion engine design is undergoing important changes to meet stricter standards concerning engine and exhaust gas emissions. One major change in engine design is the feeding of blow-by gases from the crankcase zone of the engine into the intake air-fuel mixture at the carburetor just below the throttle plate, rather than venting these gases to the atmosphere as in the past. The blow-by gases contain substantial amounts of deposit forming substances and are known to form deposits in and around the throttle plate area of the carburetor. Another significant change is the recirculation of a part of the exhaust gases to the fuel air intake of the engine. These exhaust gases also have deposit forming tendencies. The deposits caused by the recirculated gases both blow-by and exhaust gases restrict the flow of air through the carburetor at idle and at low speeds so that an overrich fuel mixture results. This condition produces rough engine idling and stalling and leads to the release of excessive hydrocarbon exhaust emissions to the atmosphere.
The noted design changes while effective for promoting a cleaner exhaust from the engine also lead a fouling of the carburetor and therefore dictate the need for an effective detergent fuel composition in order to maintain the cleanliness and efficiency of the carburetor.
2. Description of the Prior Art
U.S. Pat. No. 3,676,089 discloses a motor fuel composition containing an N-polyamine-substituted succinimide which promotes engine cleanliness particularly of the engine intake valves and ports.